The present invention relates to a solid lipstick composition comprising a polypropyl silsesquioxane film forming resin, a silicone acrylate copolymer, a volatile hydrocarbon solvent, a wax and colorant, wherein the ratio of the silicon acrylate copolymer to the polypropyl silsesquioxane resin is from about 1:1 to about 1:4, said composition preferably having a hardness of at least 40 gf for an 8.1 mm diameter stick.
The use of polyorganosiloxane-containing polymers in cosmetic compositions, including lipsticks, is discussed, for example in U.S. Pat. No. 7,879,316. The use of silicone acrylate copolymers and polypropylsilsesquioxane resins in liquid lipstick compositions has been described, for example, in US2007/0093619 and US2012/0301415.
It is desirable to use silicone polymers in combination with high amounts (e.g. greater than about 30%, more typically greater than 40%) of volatile hydrocarbon solvents in cosmetic compositions as these ingredients can improve the properties of such compositions. However, cosmetic compositions containing silicone polymers and high amounts of volatile hydrocarbon solvents are typically limited to liquid/gel formats due to the softening effects these polymers, as well as the volatile hydrocarbon solvents, have on the resulting compositions. Id. A high volatile solvent load makes it particularly challenging to achieve a solid lipstick with acceptable hardness.
There remains a need for a cosmetic composition, in particular a lipstick that includes a silicone polymer and a high amount of volatile hydrocarbon solvents and yet is hard enough to afford a solid format.
Surprisingly, applicants have found that combining a polypropylsilsesquioxane film forming resin with a silicone acrylate copolymer in a particular ratio counteracts the softening effect that the silicon polymer typically imparts to a cosmetic composition, thereby yielding a composition that is sufficiently hard so as to enable a solid format, such as a solid lipstick. It is also surprising that even with the high amount of volatile hydrocarbon solvents used to solubilize the silicone film former, the resulting composition still yields a solid lipstick, which when applied to lips and once the volatile solvents evaporate, yields a superior film with increased spread ability.
It is particularly surprising that the use of the polypropylsilsesquioxane film forming resin increases the hardness of the composition sufficiently to afford a solid lipstick even without the large amounts of waxes and fillers typically required as hardening agents. Most solid cosmetic compositions, particularly lipsticks, require either hardening ingredients (such as waxes and fillers) in amounts typically greater than about 15%, or the reduction of solvents, to afford solid compositions having acceptable hardness. In contrast, the compositions of the invention include high amounts of volatile solvents (greater than 30%, typically greater than 40%) and relatively low amounts of waxes and fillers (20% or less, typically less than 15%).